Roofing shingle with polymer film backing

ABSTRACT

A roofing shingle is a composite sheet which includes a roofing substrate having a front side and a back side. An asphalt material impregnates the substrate and coats at least the front side of the substrate. A polymer film is attached to the back side of the substrate and forms a back surface of the roofing shingle. The polymer film was applied to the substrate in the form of a film. The roofing shingle does not include backdust on the back surface. The composite sheet is formed into the size and shape of the roofing shingle. A method of manufacturing roofing shingles includes continuously supplying a roofing substrate having a front side and a back side. An asphalt material is applied to the substrate so that it impregnates the substrate and coats at least the front side of the substrate. A composite sheet is produced by providing a polymer film and attaching the polymer film to the back side of the substrate in a manner that avoids applying backdust to the substrate so that the polymer film forms a back surface of the composite sheet. The composite sheet is cut into roofing shingles while maintaining the back surface free of backdust.

TECHNICAL FIELD

This invention relates to building construction materials and moreparticularly to asphalt roofing shingles.

BACKGROUND OF THE INVENTION

In a typical roofing shingle manufacturing process, a continuous roofingsubstrate, such as a glass fiber mat or an organic felt, is passed intocontact with a coater where it is impregnated and coated with a moltenasphalt material. Roofing granules are applied on the front surface ofthe coated substrate. The coated substrate is cooled and then cut intoindividual shingles.

Typically a fine particulate material known as a “backdust” is appliedon the back surface of the coated substrate. The backdust prevents theroofing shingles from sticking together when they are stacked in abundle. Some examples of particulate materials that have been usedinclude sand, talc and other crushed rocks or minerals.

U.S. Patent Application Publication No. 2007/0218250 A1 assigned to ElkPremium Building Products, published Sep. 20, 2007, discloses roofingshingles that are made without a backdust material. The roofing shinglesinclude a substrate, an asphalt material coating the front side of thesubstrate, and roofing granules disposed on the asphalt material coatedon the substrate. The shingles also include a hot melt material, appliedto the back side of the substrate, which replaces the backdust material.

SUMMARY OF THE INVENTION

A roofing shingle is a composite sheet which includes a roofingsubstrate having a front side and a back side. An asphalt materialimpregnates the substrate and coats at least the front side of thesubstrate. A polymer film is attached to the back side of the substrateand forms a back surface of the roofing shingle. The polymer film isapplied to the substrate in the form of a film. The roofing shingle doesnot include backdust on the back surface. The composite sheet is formedinto the size and shape of the roofing shingle.

A method of manufacturing roofing shingles includes continuouslysupplying a roofing substrate having a front side and a back side. Anasphalt material is applied to the substrate so that it impregnates thesubstrate and coats at least the front side of the substrate. Acomposite sheet is produced by providing a polymer film and attachingthe polymer film to the back side of the substrate in a manner thatavoids applying backdust to the substrate so that the polymer film formsa back surface of the composite sheet. The composite sheet is cut intoroofing shingles while maintaining the back surface free of backdust.

Various additional aspects of the roofing shingles and their manufacturewill become apparent to those skilled in the art from the followingdetailed description and the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic elevational view, partially in cross section, of aportion of an apparatus for making roofing shingles according to theinvention.

FIG. 2 is a schematic plan view of a portion of an asphalt-coated sheet,showing a roofing shingle made according to the invention.

FIG. 3 is an enlarged schematic cross-sectional elevational view of afirst embodiment of a roofing shingle according to the invention.

FIG. 4 is an enlarged schematic cross-sectional elevational view of asecond embodiment of a roofing shingle according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to roofing shingles in which a polymerfilm is attached to the back side of the shingles as a replacement forthe backdust typically used on shingles. The roofing shingles will bedescribed in more detail below, after a description of an example of amethod of making the shingles.

Referring now to the drawings, there is shown in FIG. 1 an apparatus 10for manufacturing asphalt-based roofing shingles according to theinvention. The illustrated manufacturing process involves passing acontinuous sheet in a machine direction (indicated by an arrow 12)through a series of manufacturing operations. The sheet usually moves ata speed from about 300 feet/minute to about 800 feet/minute, but otherspeeds can be used.

In a first step of the manufacturing process, a continuous sheet ofshingle mat 14 is payed out from a roll (not shown). The shingle mat 14can be any type of substrate suitable for use in reinforcingasphalt-based roofing shingles, such as a web, scrim or felt ofsynthetic or natural fibrous materials. The fibrous materials mayinclude, for example, glass fibers, other mineral fibers, polymerfibers, carbon fibers, cellulose fibers, rag fibers, or mixtures ofthese fibers. Suitable mineral fibers may include fibers of aheat-softenable mineral material, such as glass, ceramic, rock, slag, orbasalt. In one embodiment, the shingle mat is a nonwoven web of glassfibers.

The shingle mat 14 is fed, in machine direction 12, through a coater 16where a coating of asphalt material 18 is applied to the shingle mat 14.The asphalt material 18 can include any materials suitable for coatingasphalt-based roofing shingles. The asphalt material 18 includesasphalt, by which is meant any type of bituminous material suitable forcoating roofing shingles, such as asphalt, tar or pitch, or anycompatible mixture of different materials. The asphalt material usuallyincludes at least about 20% asphalt by weight, and often at least about40%. The asphalt material can also include various additives and/ormodifiers, such as inorganic fillers or mineral stabilizers. In atypical asphalt roofing shingle, the coating material includes asphaltand a filler of finely ground inorganic particulate matter, such asground limestone, dolomite or silica, in an amount of from about 40% toabout 80% by weight of the asphalt material. The asphalt material canalso be modified with any suitable polymeric material, which can bevirgin polymers or recycled polymers, to make a polymer modifiedasphalt. The asphalt material can also be treated in any suitable mannerwith any suitable materials, such as ferric chloride treated orphosphoric acid treated. The asphalt material can have any suitablephysical properties. In one embodiment, the asphalt material has asoftening point in a range from about 190° F. to about 300° F., but inother embodiments the softening point can be higher or lower.

The asphalt coating 18 can be applied in any suitable manner. In theillustrated embodiment, the shingle mat 14 contacts a supply of hot,melted asphalt material 18 from a coater 16 to coat the shingle mat 14with a tacky coating of asphalt material 18. However, in otherembodiments, the asphalt coating 18 could be sprayed on, rolled on, orapplied to the shingle mat 14 by other means. For example, the asphaltcoating could be formed into an emulsion or a cutback and be coldapplied. The asphalt material impregnates the shingle mat and coats atleast the front side of the mat. The “front side” is the side of the matfacing away from the roof when the roofing shingle is installed on aroof, and the “back side” is the side of the mat facing toward the roof.

In one embodiment, the asphalt material impregnates the shingle mat andcoats the front side of the mat, but it does not coat the back side ofthe mat. In another embodiment, the asphalt material impregnates theshingle mat and coats both the front and back sides of the mat. Thecoating apparatus can include any suitable equipment to control theamount of coating on the back side of the mat. For example, theequipment can include a scraper (not shown) or similar apparatus, and/orone or more rolls (not shown), to remove coating from the back side ofthe mat in a controlled manner. The structure of the roofing mat,including the coating, is further described below.

The shingle mat 14 exits the coater 16 as an asphalt-coated sheet 20.The asphalt coating 18 on the asphalt-coated sheet 20 remains hot.

The asphalt-coated sheet 20 is shown in more detail in FIG. 2. As shown,the asphalt-coated sheet 20 for the three-wide apparatus 10 comprisessix distinct regions or lanes including three headlap lanes h1, h2, andh3, and three prime lanes p1, p2, and p3. An exemplary roofing shingleis shown by a phantom line 22 and may be cut from asphalt-coated sheet20 as shown. In this manner, three roofing shingles of any lengthdesired may be cut from each such section of asphalt-coated sheet 20.Each shingle 22 would contain one headlap lane h1, h2, or h3, and onerespective adjacent prime lane p1, p2, or p3. Accordingly, the shingle22 includes a headlap region 26 and a prime region 24.

The headlap region 26 of the shingle 22 is that portion which is coveredby adjacent shingles when the shingle 22 is ultimately installed upon aroof. The prime region 24 of the shingle 22 is that portion whichremains exposed when the shingle 22 is ultimately installed upon a roof.

In this embodiment, the shingle 22 is cut from the asphalt-coated sheet20 to be three feet long by one foot wide. As further shown in FIG. 2,the shingle 22 includes two cut-out regions 28 which define three tabs30. It will be apparent to one skilled in the art that theasphalt-coated sheet 20 may be manufactured having a wide variety ofwidths to allow different numbers of shingles to be cut therefrom. Forexample, some roofing shingle manufacturing plants use an asphalt-coatedsheet (not shown) which is sufficiently wide to allow four, one footwide shingles to be cut therefrom. Such a wider asphalt-coated sheetwould include an additional headlap region, and an additional primeregion. Other manufacturing plants use an asphalt-coated sheet (notshown) which is sufficiently wide to allow six, one foot wide shinglesto be cut therefrom. One skilled in the art will also recognize thatroofing shingles of different sizes, i.e. roofing shingles havingdifferent lengths and/or widths, may be cut from the asphalt-coatedsheet 20. Instead of three-tab roofing shingles as shown in FIG. 2,alternatively the shingle manufacturing apparatus can be set up formanufacturing laminated roofing shingles (not shown) or any other typesof asphalt-based shingles. The manufacture of laminated shinglestypically includes adhering the backs of one section of asphalt-coatedsheet to the tops of another section.

As further illustrated in FIG. 1, a polymer film 72 is fed from a roll74 onto the back side 21 of the asphalt-coated sheet 20 after it exitsthe coater 16. Another roll 75 presses the film against the sheet. Thehot asphalt coating 18 on the sheet can help the film to adhere to thesheet. The polymer film 72 is described in more detail below. Althoughthe embodiment shown in FIG. 1 illustrates one example of a method ofapplying the polymer film to the back side of the sheet, it should berecognized that the polymer film can be applied by any suitable method.Also, the polymer film can be applied at any suitable location duringthe manufacturing process. For example, it could be applied after theroofing granules are applied as described below.

As further illustrated in FIG. 1, the asphalt-coated sheet 20 is passedbeneath a series of granule applicators 56 and 58 for applying prime andheadlap granules onto the coated sheet. The granule applicators can beof any type of applicator, blender or dispenser suitable for applyinggranules onto the coated sheet, such as for example a fluted rollapplicator, gravity feed applicator or an auger-type dispenser. Anexample of a granule applicator, 56 and 58, is a granule applicator ofthe type disclosed in U.S. Pat. No. 5,599,581 to Burton et al., which ishereby incorporated by reference, in its entirety. Additionally, agranule valve such as the granule valve disclosed in U.S. Pat. No.6,610,147 to Aschenbeck may also be used. U.S. Pat. No. 6,610,147 toAschenbeck is also incorporated by reference in its entirety. In theembodiment shown, the prime granule applicator 56 is fed from a primegranule hopper 60 via a prime granule hose 60 a. The headlap applicator58 can be fed by similar apparatus (not shown).

Although two granule applicators 56 and 58 are shown in the embodimentillustrated in FIG. 1, any suitable number and configuration of granuleapplicators can be used. For example, a series of two prime granuleapplicators can be used, wherein the granule applicator 56 can be usedto apply prime granules 57 onto the prime lanes p1, p2 and p3 as shownin FIG. 2. Similarly, the granule applicator 58 can be used to applyheadlap granules 59 on the headlap lanes h1, h2 and h3 as shown in FIG.2. Applying prime granules 57 and headlap granules to the coated sheet20 defines a granule-covered sheet 62. In another embodiment (notshown), additional granule applicators can be used for additionalgranule drops, such as different colors, sharp demarcations andbackground granules.

As shown in FIG. 1, after all the granules are deposited on theasphalt-coated sheet 20, the granule-covered sheet 62 is turned around aslate drum 64 to press the prime granules 57 and headlap granules 59into the asphalt coating 18. The slate drum 64 temporarily inverts thegranule-covered sheet 62 so that the excess and non-adhering granulesfall off. The excess granules fall into a backfall container 70 and arerecovered for later use. The granule covered sheet is turned around adrum 78. The granule-covered sheet 62 is passed between a pair of pressrolls 80, 82 that further press the prime granules 57 and headlapgranules 59 into the granule-covered sheet 62.

As further shown in FIG. 1, downstream from the press rolls, 80 and 82,the granule covered-sheet 62 is passed through a cooling section 84. Thecooling section 84 is configured to sufficiently cool thegranule-covered sheet 62 to allow downstream manufacturing operations.In one embodiment, the cooling section 84 includes rollers allowing thegranule-covered sheet 62 to be passed up and down while being sprayedwith water to cool the hot asphalt coating 18. In another embodiment,any means of cooling the granule-covered sheet 62 can be used. Alaminated roofing shingle has additional process steps.

Downstream from the cooling section 84, the granule-covered sheet 62 issubsequently fed through a cutter 86 that cuts the granule-covered sheet62 into individual shingles 22. The cutter 86 may be any type of cutter,such as for example a rotary cutter, sufficient to cut thegranule-covered sheet 62 into individual shingles 22.

FIG. 3 shows a cross-section, taken through the prime region, of a firstembodiment of a roofing shingle 22 according to the invention. Theroofing shingle 22 includes a roofing mat 14 or substrate. The roofingmat 14 has a front side 14 f and a back side 14 b. An asphalt material18 impregnates the roofing mat 14 and coats the front side 14 f of themat. In the embodiment shown in FIG. 3, the asphalt material 18 does notcoat the back side 14 b of the mat. However, FIG. 4 (described below)shows an embodiment in which the asphalt material coats both the frontside and the back side of the mat. Prime granules 57 are embedded in thefront surface of the asphalt material 18.

A polymer film 72 is attached to the back side of the roofing mat andforms a back surface of the roofing shingle 22. The polymer filmreplaces the backdust typically included on roofing shingles. Thepolymer film can be made from any suitable material(s), and it can haveany suitable structure and properties. By “film” is meant asubstantially continuous sheet of polymer, in contrast to discontinuousstructures such as woven or nonwoven sheets or webs.

The polymer film 72 can be attached to the back side of the roofing matby any suitable method. For example, the surface of the film can beheated (not shown) to make it soft so that it adheres to the mat duringproduction of the shingle. Alternatively, the polymer film can be aself-adhering film similar to Scotch brand adhesive tape. Alternatively,any suitable adhesive (not shown) can be used for adhering the polymerfilm to the roofing mat during production of the shingle.

The polymer film can be produced from any suitable polymer or anysuitable blend of different polymers. Some examples of polymers that maybe used to produce the polymer film include polyolefins such aspolypropylene and polyethylene; or polyesters such as polyethyleneterephthalate, polyethylene naphthalate or polybutylene terephthalate.Either low density or high density polyolefins could be used. In someembodiments, a polymer such as a polyamide, for example nylon, can beblended with the polyolefin or polyester to control the melt temperatureor other properties of the film. Also, in some embodiments, the polymerexcludes materials such as polyvinyl chloride, polycarbonate, ionomerresin and polyvinylidene chloride. In contrast to the roofing shinglesdisclosed in U.S. 2007/0218250 A1, the film is not a hot melt material.

The polymer film can include conventional additives such asantioxidants, delusterants, pigments, fillers such as silica, calciumcarbonate, kaolin, titanium dioxide, antistatic agents and the like, ormixtures thereof.

The polymer film can be produced by any suitable method, such as any ofthose known in the art. In one method of making a relatively highstrength polymer film, the polymer is melted and extruded as anamorphous sheet onto a revolving casting drum to form a cast sheet ofthe polymer. The sheet is cooled and then stretch oriented in one ormore directions to impart strength and toughness to the film. Wherenecessary, the film is heat treated after stretching to lock in theproperties by further crystallizing the film.

The polymer film can have any suitable thickness. Depending on the typeof polymer used, and depending on whether or not the film is used tostrengthen the roofing shingle, the thickness of the film can vary overa wide range. For example, in some embodiments the polymer film has athickness within a range of from about 0.05 mil to about 35 mils, andmore particularly from about 0.3 mil to about 20 mils. In someembodiments the polymer film is a relatively thin film, for example,having a thickness within a range of from about 0.05 mil to about 10mils, and more particularly from about 0.3 mil to about 6 mils. In otherembodiments the polymer film is a relatively thick film, for example,having a thickness within a range of from about 10 mils to about 35mils.

Different approaches may be taken in the selection of the polymer film.In some embodiments, the polymer film is a relatively high strength filmthat not only functions as a parting agent like backdust, but that alsobuilds significant strength properties into the roofing shingle. Forexample, the polymer film may have a tear strength of at least about1500 g, more particularly at least about 1700 g, and more particularlyat least about 2000 g. The tear strength measurement can be theElmendorf tear strength measured in accordance with ASTM Method D1922,although any other suitable strength measurement can be used. Someexamples of relatively high strength films include oriented polyethyleneor polypropylene films, or films made from a blend of polyethylene orpolypropylene with a high strength polymer such as nylon.

The use of a relatively high strength film could enable the productionof a higher strength roofing shingle, or it could enable the productionof a roofing shingle having the same strength but including a lowerstrength roofing mat. In one embodiment, the roofing mat is a relativelylightweight mat weighing not more than about 1.6 lb/100 ft², and thepolymer film has sufficient strength to maintain the strength of theroofing shingle with the lightweight mat. For example, a current roofingshingle having sufficient strength may include a roofing mat having aweight of 1.95 lb/100 ft², but a roofing shingle made with a polymerfilm may be able to use a roofing mat having a weight of 1.3-1.5 lb/100ft² while obtaining the same shingle strength.

In other embodiments, the polymer film is a relatively low strength filmthat functions as a parting agent like backdust but that does notprovide any significant strength to the roofing shingle. For example,the polymer film may have a strength of less than about 1000 g, moreparticularly less than about 500 g, and more particularly less thanabout 100 g. Some examples of relatively low strength polymer filmsinclude non-oriented polymer films, films made from recycled polymers,and/or very thin films. For example, the polyethylene films used toproduce garbage bags are usually relatively thin and low strength films.

FIG. 4 shows a cross-section, taken through the prime region, of asecond embodiment of a roofing shingle 23 according to the invention.The roofing shingle 23 includes a roofing mat 14 or substrate. Theroofing mat 14 has a front side 14 f and a back side 14 b. An asphaltmaterial 18 impregnates the roofing mat 14 and coats the front side 14 fof the mat. Prime granules 57 are embedded in the front surface of theasphalt material 18. A layer 19 of the asphalt material 18 also coatsthe back side 14 b of the mat. A polymer film 72 is attached to the backside of the layer 19 of asphalt material and forms a back surface of theroofing shingle 23. In one embodiment, the layer 19 of asphalt material18 is a relatively thin layer that is just thick enough to act as anadhesive, when molten during the production of the shingle, to bond thepolymer film 72 to the roofing mat 14. For example, a relatively thinlayer 19 of asphalt material 18 may have a thickness within a range offrom about 0.5 mils to about 5 mils. Optionally, the asphalt material 18or the polymer film 72 can be modified in any suitable manner tofacilitate the bonding and/or to increase the strength of the bond. Inanother embodiment, the layer 19 of asphalt material 18 may have a widerthickness range, for example, a thickness within a range of from about 1mil to about 20 mils, and more particularly from about 3 mils to about 9mils.

The principle and mode of operation of this invention have beendescribed in its preferred embodiments. However, it should be noted thatthis invention may be practiced otherwise than as specificallyillustrated and described without departing from its scope.

1. A roofing shingle which is a composite sheet comprising: a roofingsubstrate having a front side and a back side; an asphalt materialimpregnating the substrate and coating at least the front side of thesubstrate; and a polymer film attached to the back side of the substrateand forming a back surface of the roofing shingle, the polymer filmhaving been applied to the substrate in the form of a film; the roofingshingle not including backdust on the back surface; the composite sheetbeing formed into the size and shape of the roofing shingle.
 2. Theroofing shingle of claim 1 wherein the polymer film is attached to thesubstrate with substantially none of the asphalt material between thefilm and the substrate.
 3. The roofing shingle of claim 2 wherein thepolymer film is attached to the substrate by an adhesive.
 4. The roofingshingle of claim 2 wherein the polymer film is attached to the substrateby the surface of the film having been softened so that it adheres tothe substrate.
 5. The roofing shingle of claim 1 wherein the asphaltmaterial is also disposed on the back side of the substrate, and theasphalt material adheres the polymer film to the substrate.
 6. Theroofing shingle of claim 1 further comprising roofing granules appliedto the asphalt material coating the front side of the substrate.
 7. Theroofing shingle of claim 1 consisting of the substrate, the asphaltmaterial, the polymer film, optionally roofing granules, and optionallyadhesive.
 8. The roofing shingle of claim 1 wherein the substrate is arelatively lightweight substrate weighing not more than about 1.6 lb/100ft², the polymer film having sufficient strength to maintain thestrength of the roofing shingle with the lightweight substrate.
 9. Theroofing shingle of claim 1 wherein the polymer film has a thicknesswithin a range of from about 0.05 mil to about 10 mils.
 10. The roofingshingle of claim 1 wherein the polymer film has a thickness within arange of from about 10 mils to about 35 mils.
 11. The roofing shingle ofclaim 1 wherein the polymer film is made from a polyolefin, a polyester,or a blend thereof.
 12. A method of manufacturing roofing shinglescomprising: continuously supplying a roofing substrate having a frontside and a back side; applying an asphalt material to the substrate sothat it impregnates the substrate and coats at least the front side ofthe substrate; producing a composite sheet by providing a polymer filmand attaching the polymer film to the back side of the substrate in amanner that avoids applying backdust to the substrate so that thepolymer film forms a back surface of the composite sheet; and cuttingthe composite sheet into roofing shingles while maintaining the backsurface free of backdust.
 13. The method of claim 12 wherein the polymerfilm is attached to the substrate with substantially none of the asphaltmaterial between the film and the substrate.
 14. The method of claim 13wherein the polymer film is attached to the substrate by an adhesive.15. The method of claim 13 wherein the polymer film is attached to thesubstrate by softening the surface of the film so that it adheres to thesubstrate.
 16. The method of claim 12 wherein the asphalt material isalso disposed on the back side of the substrate, and the asphaltmaterial adheres the polymer film to the substrate.
 17. The method ofclaim 12 further comprising embedding roofing granules in the asphaltmaterial coating the front side of the substrate.
 18. The method ofclaim 12 consisting of supplying the substrate, applying the asphaltmaterial, attaching the polymer film, optionally applying roofinggranules to the asphalt material coating the front side of thesubstrate, and optionally using an adhesive to attach the film.
 19. Themethod of claim 12 wherein the substrate supplied is a relativelylightweight substrate weighing not more than about 1.6 lb/100 ft², andthe polymer film attached has sufficient strength to maintain thestrength of the roofing shingle with the lightweight substrate.
 20. Themethod of claim 12 wherein the polymer film which is attached has athickness within a range of from about 0.05 mil to about 10 mils. 21.The method of claim 12 wherein the polymer film which is attached has athickness within a range of from about 10 mils to about 35 mils.
 22. Themethod of claim 12 wherein the polymer film is made from a polyolefin, apolyester, or a blend thereof.